Tobacco smoke is the only known causative environmental agent for cancer of the pancreas. We have demonstrated that tobacco-specific nitrosamines (TSNA), such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), the only known tobacco-derived products that induce cancer of the pancreas in rats, are present in human pancreatic juice. The fat content and the type of fat [omega-3 vs. omega-6 polyunsaturated fatty acids (PUFA)] of the diet play an important role in the induction of cancer. We have also demonstrated that a high-fat (HF, 23.5% corn oil) diet increases the carcinogenic potency of NNK in the pancreas ofF344 rats; however, the mechanisms responsible for the enhancing effects of HF remain to be determined. It is our hypothesis that TSNA can induce pancreatic cancer in smokers and that consumption of diets high in omega-6 PUFA enhances this effect. Specifically, omega-6 PUFA will induce increasingly higher levels of COX-2 expression with progressive stages of pancreatic carcinogenesis in smokers and in rats treated with NNK. We will test this hypothesis in the following specific aims: (1) elucidate biochemical and molecular mechanisms responsible for the modulating effects of omega-6 PUFA and omega-3 PUFA on NNK-induced pancreatic cancer using our previously established rat animal model assay (2) compare the capacity of NNK and its metabolites (S)- and (R)-NNAL to induce malignant transformation in human ductal pancreatic cells (3) conduct pilot studies, using selected biomarkers, to establish the association between exposure to tobacco carcinogens, the type and amount of fat, and the development of pancreatic cancer. The result of this study will further support the role of cigarette smoking and underscore the likelihood of dietary fat as a modulator of the development of human pancreatic cancer that is suggested by epidemiological observations.